Rotary switch assembly with coupling means and rotatable conductive slip ring structure



March 22. 1966 G. E. VAN VOLKENBURG ETAL 3,

ROTARY SWITCH ASSEMBLY WITH COUPLING MEANS AND ROTATABLE CONDUGTIVE SLIP RING STRUCTURE Filed April 10, 1961 INVENTORS GEORGE E. VAN VOLKENBURG DONALD R. VAN VOLKENBURG FIG United States Patent ROTARY SWITCH ASSEMBLY WITH COUPLING MEANS AND ROTATABLE CONDUCTIVE SLIP RING STRUCTURE George E. Van Volkenburg, 5614 57th Ave., Hyattsville, Md., and Donald R. Van Volkenburg, 11 Franklin Ave., Medford, Mass.

Filed Apr. 10, 1961, Ser. No. 110,840 7 Claims. (Cl. 200-11) Described herein is a rotary switch designed to open or close electrical contacts as a function of the number of degrees of rotation of its shaft. The switch is adaptable to many configurations, or changes in configurations by the user. The manufacturing process utilizes the techniques of printed electronic circuits and photomechanical reproduction. The user may determine or change the switch configuration by applying or removing painted or soldered conductors. A vernier arrangement in the placement of the fixed contacts permits opening and closing of the switch with a high degree of accuracy with respect to the number of degrees of shaft rotation.

The rotary switch of the present invention is more fully described hereinbelow with reference to the drawings wherein FIGURE 1 shows a side cross-sectional view of switch assembly; FIGURES 2-4 show plan views of the principal components taken along section lines 2-2, 33, and 4-4, respectively.

The switch consists of a'disk 1 called the stationary disk, with a hole in the center in which is mounted a suitable bearing 2 and shaft 3. Twosmaller disks 4 are mounted on the shaft, one on each side of the stationary disk. The disks 4 function as a mounting for rotating switch contacts 5 and a means to mechanically couple the switch to other rotating devices. These two disks are identical except that one has a pin 16 and radial slots 17 which are used if the switch assembly is coupled to a second switch assembly. On these disks are slip rings 6 to connect the rotating contacts to brushes 7 for external connections. On the surface of each side of the stationary disk are conducting radials 8 which are the fixed contacts of the switch. The rotary contact is 3 degrees wide and slides over these fixed contacts as it rotates. Two rings 9 and 10 clamp ot the outer circumference on each side of the stationary disk. A metal strip 11 placed between the stationary disk and the adjacent ring makes a pressure contact with the fixed contacts and serves as a terminal for external wire connections. The brushes 7 consist of metal 9 and 10 clamp to the outer circumference on each side of stationary disk, and serve as terminals for external connections to the slip rings and rotating contacts.

The disks 4 attached to the shaft are made from a board of insulating material with copper-clad surface, commonly known as printed circuit board. Conventional printed circuit techniques are used to obtain the desired pattern of the slip rings and connections to the rotating contact. The slip rings are plated with a hard metal such as rhodium to prevent wear. The stationary disk is made of the same material. Printed circuit and photomechanical reproduction techniques are used to print the radial contacts and to establish their location on the surface with extreme definition and accuracy. A description of one applicable method is as follows: A large drawing of the fixed contactor pattern is prepared and then reduced to a photographic negative of the same dimensions as the desired switch pattern. Any absolute error in dimensions on the large drawing becomes smaller when considered as a percentage of the total dimension. When the large drawing is reduced to a small negative, the same percentage of error exists, but the obsolute error decreases. A copper-clad board is coated with light-sensitive material Patented Mar. 22, 1966 and exposed through the negative. The exposed surface is developed using conventional photographic methods leaving a mask of the desired contact pattern. After the exposed copper surface is removed by etching the mask material is removed. The copper sections remaining are the radial fixed contacts. These are plated with a hard metal, such as rhodium, to prevent wear.

Using the method described, fixed radial contacts are placed on one surface of the stationary disk. Each contact is 2 degrees wide. One contact is identified as the key contact 12. The key contact and 4 adjacent contacts 14 clockwise from it are spaced 2.5 degrees apart. The key contact and 4 adjacent contacts counterclockwise from it (15) are spaced 1.5 degrees apart. All other contacts are spaced 2 degrees apart. This pattern of spacing provides a vernier arrangement so that the fixed contacts can be grouped together in increments of 0.5 degree.

The user of the switch may adapt it to a desired configuration by first determining the number of degrees the switch must be closed, to the nearest 0.5 degree. By calculation, or by the use of a suitable chart or written instructions the required number and location of fixed contacts is determined. The user of the switch then connects these contacts together electrically by painting over them and the adjacent spaces with silver conducting paint 13. The rings are loosened and the metal strip 11 which is the external connection is located to make pressure contact with the fixed contacts that are connected together. When this is completed, a continuous electrical path is made between the rotary contact and the fixed contacts at the required-number of degrees of shaft rotation The user of the switch may change the configuration by removing the conducting paint with a suitable solvent and repeating the above process.

The vernier principle utilized with this switch is expressed as follows:

D=the number of degrees included in a group of connected fixed contacts N=the number of fixed contacts connected together in the group S =the number of 2.5 degree spaces included in the group S =the number of 1.5 degree spaces included in the grou I From this, many methods of determining the number and location of the fixed contacts for any given number of degrees may be devised. These may include the use of other formulae, the use of charts, written procedures, or by calculation or observation.

We claim:

1. A rotary switch assembly consisting of: a stationary disk of insulatingmaterial having a number of radials of conducting material on one side thereof to function as fixed contacts; bearing means mounted in the center of said disk; shaft means extending through said bearing means so that it rotates with its axis perpendicular to the disk; a rotary disk of non-conducting material smaller in diameter than said stationary disk attached to said shaft means; said rotary disk rotating with the shaft and having slip rings of conducting material printed thereupon, at least one contact arm attached to said rotary disk and electrically connected to the slip rings; said contact arm contacting and sliding over said radials on the stationary disk and breaking with each radial after contacting the next radial; two flat rings of insulating material placed one on top of the other on the flat surface of the stationary disk at the outer edge thereof; and electrically conducting metal strips, placed against and connecting a desired number of said radial contacts at the outer edge of the stationary disks, said two flat rings being clamped against the stationary disk and thereby securing the metal strips against the fixed contacts.

2. A rotary switch assembly as described in claim 1, including on the side of said stationary disk opposite to said radials, a similar configuration of fixed radials of conducting material, and a second rotary disk independent of said first-mentioned rotary disk attached to said shaft and carrying at least one contact arm electrically connected with the radials on said opposite side, whereby said assembly comprises a pair of switches independent of each other turning on a common shaft.

3. A rotary switch assembly as described in claim 2', a coupling pin mounted on one rotary disk, and radial slots in both rotary disks coupling the assembly to like assemblies, with the pin of one rotary disk of such size that it will couple into the slot of a rotary disk on another like assembly, and with the couplings so placed that all assemblies coupled together will have their rotors turn together about a common axis.

4. A rotary switch assembly as described in claim 1, in which after manufacture is complete, one or more metal strips are positioned to contact one or a number of fixed contacts, as required by its use, with these metal strips then clamped into permanent configuration by rings on each side of the stationary disk, and functioning as external wiring terminals for the fixed' contacts.

5. A rotary switch assembly as described in claim 1, wherein said rings and the means clamping said rings are adjustable to readily loosen and permit adjustment of said metal strips.

6. A rotary switch assembly as described in claim 1 including 90 fixed contacts 2 degrees wide, and with each one group of four adjacent spaces 1.5 degrees apart, and

an adjacent group of four adjacent spaces 2.5 degrees apart, and the remainder of the spaces 2 degrees apart,

and wherein the number of degrees included in any group of adjacent contacts is expressed by this formula,

D=4(N 1) +2+0.5S O.5S

where:

D=the number of degrees included in a group of ad jacent fixed contacts N =the number of adjacent fixed contacts S =the number of 2.5 degree spaces included in the group S =the number of 1.5 degree spaces include-d in the group.

7. A rotary switch assembly as described in claim 1 and in which the pattern of the fixed contacts on said stationary disk permits connecting the fixed contacts together, to obtain a switch with a variety of switch closures in increments that are smaller than the width of its contacts, and smaller than the space between contacts.

References Cited by the Examiner UNITED STATES PATENTS FOREIGN PATENTS 9/1959 Australia. 3/1961 Germany.

KATHLEEN H. CLAFFY, Primary Examiner.

GILHEAN Y, Examiners. 

1. A ROTARY SWITCH ASSEMBLY CONSISTING OF: A STATIONARY DISK OF INSULATING MATERIAL HAVING A NUMBER OF RADIALS OF CONDUCTING MATERIAL ON ONE SIDE THEREOF TO FUNCTION AS FIXED CONTACTS; BEARING MEANS MOUNTED IN THE CENTER OF SAID DISK; SHAFT MEANS EXTENDING THROUGH SAID BEARING MEANS SO THAT IT ROTATES WITH ITS AXIS PERPENDICULAR TO THE DISK; A ROTARY DISK OF NON-CONDUCTING MATERIAL SMALLER IN DIAMETER THAN SAID STATIONARY DISK ATTACHED TO SAID SHAFT MEANS; SAID ROTARY DISK ROTATING WITH THE SHAFT AND HAVING SLIP RINGS OF CONDUCTING MATERIAL PRINTED THEREUPON, AT LEAST ONE CONTRACT ARM ATTACHED TO SAID ROTARY DISK AND ELECTRICALLY CONNECTED TO THE SLIP RINGS; SAID CONTACT ARM CONTACTING AND SLIDING OVER SAID RADIALS ON THE STATIONARY DISK AND BREAKING WITH SAID RADIAL AFTER CONTACTING THE NEXT RADIAL; TWO FLAT RINGS OF INSULATING MATERIAL PLACED ONE ON TOP OF THE OTHER ON THE FLAT SURFACE OF THE STATIONARY DISK AT THE OUTER EDGE THEREOF; AND ELECTRICALLY CONDUCTING METAL STRIPS, PLACED AGAINST AND CONNECTING A DESIRED NUMBER OF SAID RADIAL CONTACTS AT THE OUTER EDGE OF THE STATIONARY DISKS, SAID TWO FLAT RINGS BEING CLAMPED AGAINST THE STATIONARY DISK AND THEREBY SECURING THE METAL STRIPS AGAINST THE FIXED CONTACTS. 